Sheet metal evaporator with heating means



lJam. 15, 1957 .1. s, PALMER SHEET METAL EVAPORATOR WITH HEATING MEANS 2 Sheets-Sheet l Filed July 14, 1952 INVENTOR. Jin S/Palmer BY/ O/B Q LGy,

Jan. 15, 1957 J. s. PALMER SHEET METAL EvAPoRAToE WITH HEATING MEANS 2 Sheets-Sheet 2 Filed July 14, 1952 JFT/'5.4.

United States Patent O SHEET METAL EVAPORATOR WITH HEATING MEANS John S. Palmer, Evansville, Ind., assignor, by mesue assignments, to Whirlpool-Seeger Corporation, a corporation of Delaware Application July 14, 1952, Serial No. 298,683

1 Claim. (Cl. 62126) This invention relates to refrigerating apparatus and more particularly to a refrigerant evaporator or cooling unit fashioned with an integrally arranged heating unit for defrosting purposes.

Heretofore evaporative cooling units have been proposed which included means for applying external heat thereto for the defrosting thereof, but such units as have been proposed were of such complicated design that the cost of fabrication was prohibitive. It is a principal object of this invention, therefore, to provide a highly eicient sheet metal evaporator of greatly simplified design that is inexpensively constructed and yet is sturdy and compact.

Another object is to provide a sheet metal evaporator having improved defrosting means formed therein which operate to distribute heat in a most advantageous manner and thus quickly defrost the entire evaporator.

A further object is to provide a sheet metal evaporator wherein an electrical resistance element is disposed between the sheets thereof.

A still further object is to provide a sheet metal evaporator having a pair of sinuous parallel passages, one of which is adapted to transmit refrigerant therethrough while the other is arranged to support or contain an electrical resistance heating element.

Other objects and advantages will be understoodland will become more apparent from the following description when read in conjunction with the drawings in which:

Fig. 1 is a bottom elevation of the two sheets from which the evaporator is fashioned, shown in a developed relation prior to the bending thereof;

Fig. 2 is a section taken on line 2-2 of Fig. l;

Fig. 3 is a front edge elevation of an evaporator constructed according to the proposed invention;

Fig. 4 is an end elevation of the proposed evaporator and includes a schematic representation of the complete refrigeration apparatus;

Fig. 5 is a section taken on line 5 5 of Fig. 4; and

Fig. 6 is a section similar to Fig. 5 but shows a slight modification of the electrical resistance heating element arranged in the evaporator.

Referring now to the drawing it will be noted the evaporator, represented generally by the numeral 10, comprises two superimposed metal sheets 11 and 12, preferably of substantially rectangular shape. As illustrated the sheet 11 is embossed with parallel extending arcuate depressions that form a pair of spaced apart continuous sinuous or serpentine corrugations 13 and 14, While the sheet 12 is at. If desired, of course, the depressions could be formed partially in each plate in a complemental or mating relation instead of all in one plate as shown herein. The sheet 11 is superimposed upon the sheet 12 and the two suitably secured together along the at portions, between the corrugations 13 and 14, and along the edges of the sheets. In the preferred embodiment illustrated the copper brazing process utilizing a hydrogen furnace has been employed for suitably 2,777,300 lsatnted Jan. 15, 1957 securing the sheets 11 and 12 along all adjoining points of contact, and particularly in the areas indicated, respectively, by the reference numerals 15 and 16. It will be appreciated, however, that other securing methods or means such, for instance, as the roller weld, the seam weld or the continuous spot weld may also be employed for fxedly securing the two sheets together without deviating from the spirit of the invention, and that the copper brazing process indicated herein is merely illustrative.

As thus fashioned there is formed a continuous sinuous passage 14 which will permit the passage of refrigerant therethrough, and, in doing so, will act as an expansion chamber for the liquid or vaporized refrigerant as is well understood in the art. One end of said passage 14 may be connected by a discharge conduit 17 to the inlet of a refrigerant motor-compressor 18, the discharge outlet of which is connected by a conduit 19 to a condenser 20 whose discharge outlet, in turn, connects with a capillary restrictor tube 21 the discharge end of which is connected to the opposite end of said passage 14. Since the operation of the refrigeration apparatus is generally conventional a further detailed explanation thereof is believed unnecessary.

Now in accordance with the specific teachings of the present invention there is disposed within the sinuous passage 1.3 an electrical resistance heating element indicated generally by the reference numeral 22. The heating element 22, which may be any of several such elements generally available on the commercial markets, comprises a centrally disposed electrical resistance wire 23 surrounded by electrical insulating material 24, in turn, covered with a metallic skin-like sheath 25. Said heating element is, of course, positioned in the arcuate depression 13, in sheet 11, prior to the time that the flat sheet 12 is superimposed thereon and the two sheets secured together. The element 22 is dimensioned, preferably, so that it substantially iills the interior of said sinuous passage 13. Opposite ends of the resistance Wire 23, of said element, are adapted for connection to a suitable source of electrical energy (not shown) which, in turn, may be automatically controlled for energizing said element at prescribed time intervals, in accordance with standard practices in the refrigeration art.

In Fig. 6 there is illustrated an optional or modified form of construction that may be provided, if desired, for the electrical heating element 22. In the modified form `the metallic outer sheath is omitted and the heating element includes a centrally disposed resistance wire 23a that is surrounded by electrical insulating material 24a all of which is disposed in the passage 13 and sealed therein.

In both forms of the invention the ends of the electrical resistance unit may also be cerarnically insulated, in accordance with standard practices, to prevent any possible short circuiting of electrical currents supplied to said heater element.

After the two superposed plates have been suitably secured together Iand the selected heater element disposed therein the plate assembly is bent or folded along the broken lines 25, 26, 27 and 28 to form the U-shaped evaporator shown in Fig. 3. The turned-in portions at opposite ends thereof provide llanges 29 and 30 which may be utilized for aflixing said evaporator to the inner liner of a refrigerator cabinet or like structure.

It will now be apparent from the foregoing that a novel and inexpensive sheet metal evaporator containing built-in electric heater defrosting means has been shown and described, and it is to be understood that changes m-ay bev made in the construction without de- 3 parting from the spirit of the invention lor the scope thereof as dened in the appended claim.

What is claimed is:

A defrosting evaporator for household refrigerators, comprising a pair of kplates of substantially rectangular lform, one of said plates being .embossed outwardly to form one continuous larger groove, which is sinuous throughout its length yan-d is closed by the otherplate for ya refrigerant conduit, said conduit including Lan open ,-V-shaped formation `at each end of the plate, each of which is joined :to one of afpair of central sinuous format-ions, each having a plurality of center to end passes with U-shaped joining portions, and including a long pass joining the pair 'of central sinuous portions, one of said `plates also having ra smaller groove following and close to the side of said larger groove to form a continuous cavity for an electric heater, and a bendable, insulated electric heater located inside said Cil smaller groove, before the joining of said plates, and enclosed inside both sheets to spread its heat outwardly through the plates, for defrosting the entire evaporator quickly, the said plates being integrally secured together at all other areas except said grooves, and being bent to top open U shape, with inwardly extending attaching anges at the top.

References Cited in the file of this patent UNITED STATES PATENTS 2,492,397 Peterson Dec. 27, 1949 2,516,864 Gilmore et al. Aug. ,1, 1950 2,541,201 Buecken ct al. Feb. 13, 1951 2,601,466 Thomas June 24, 1952 2,638,754 Kleist May 19, 1953 2,665,567 King et al. Ian. 12, 1954 2,685,780 Zearfoss Aug. 10, 1954 2,691,871 Saler .V Oct. 19, V1,954 

